Dawson Miller

eLife Assessment This valuable study describes a software package in R for visualizing metabolite ratio pairs. The evidence supporting the claims of the authors is solid and broadly supports the authors' conclusions. This work would be of interest to the mass spectrometry community.

Supporting Information Filename Description pcmr13177-sup-0001-AppendixS1.docxWord 2007 document , 721.4 KB Appendix S1. REFERENCES , , , , & (2016). TPC2 controls pigmentation by regulating melanosome pH and size. Proceedings of the National Academy of Sciences of the United States of America, 113(20), 5622–5627. https://doi.org/10.1073/pnas.1600108113 , , & (2001). Melanosomal pH, pink locus protein and their roles in melanogenesis. The Journal of Investigative Dermatology, 117(1), 158–159.

Abstract Mass spectrometry imaging (MSI) is a powerful technology used to define the spatial distribution and relative abundance of structurally identified and yet-undefined metabolites across tissue cryosections. While numerous software packages enable pixel-by-pixel imaging of individual metabolites, the research community lacks a discovery tool that images all metabolite abundance ratio pairs.